1. Field of the Invention
The invention relates to the field of reverberators and reverberation systems.
2. Prior Art
Reverberators, particularly mechanical, spring reverberators have been utilized for furnishing artificial reverberations to a sound signal from a recorder, radio, musical instrument, or other type of devices. The purpose of this reverberation is to simulate the reverberation effect of a room or hall, of appropriate acoustical properties within a relatively small listening space. Spring reverberators, such as those disclosed in U.S. Pat. No. 2,982,819 and 3,106,610 have been successfully used for this purpose and provide a relatively low cost reverberation means when compared to echo chambers, or the like. These reverberators generally consist of pairs of springs with slightly different time delays, driven in a torsional mode by a transducer. One major drawback to these spring reverberators is that they have a relatively low cutoff frequency of approximately 5kHz.
Because of certain inherent characteristics of these spring reverberators, it has been impractical to extend the frequency range of these devices. One reason for this is that the frequency cutoff beyond 4.5kHz is extremely rapid. Also, the decay time of the reverberations (i.e. the time in seconds necessary for the sound to decay from its steady state value to 60db below that value, after excitation is removed) becomes unsatisfactorily short. Moreover, these reverberations exhibit subjectively unpleasant coloration above 5kHz.
As will be seen the present invention utilizes two spring reverberators; however, through use of frequency shifting the range of the reverberations are extended to beyond 9kHz. This is accomplished utilizing standard, commercially available components.